The invention relates to a dishwasher comprising washing liquid lines for conveying washing liquid to spray devices for spraying washing liquid onto items to be washed and in particular a method for self-cleaning of washing liquid lines in dishwashers.
Dishwashers with spray devices are known wherein the washing liquid is sprayed onto the items to be cleaned during the washing mode by means of spray devices, such as rotating spray arms, for example. For this purpose, the washing liquid is supplied to the rotating spray arms by a circulating pump via washing liquid lines and the liquid emerges under pressure from spray nozzles and impinges upon the items to be washed. In conventional dishwashers the circulating pump can usually only be operated in one direction of rotation so that the washing liquid only flows in one direction through the washing liquid lines and the spray device. The washing liquid circulated during the washing mode also entrains wash residues which can be deposited in the washing liquid lines and in the spray devices, which can hinder the flow of washing liquid to the extent of causing blockages of the washing liquid lines and spray devices.
Known from DE 197 02 982 is a dishwasher wherein during the washing mode washing liquid is pumped into rotating spray arms via washing liquid lines by a circulating pump. During a pumping-out mode the washing liquid is conveyed from the dishwasher by a drain pump, the circulating pump being temporarily operated in the opposite direction of rotation in order to completely extract the washing liquid from the washing liquid lines and the spray arms. This dishwasher has the disadvantage that during the pumping-out mode washing liquid is merely removed from the washing liquid lines and the spray arms without achieving any cleaning effect in the washing liquid lines.